System for controlling slurry on a counter current belt washer

ABSTRACT

A traveling deckle is adapted to run on each edge of a filter belt in a counter current belt washer system. The traveling deckle may be used to retain a slurry on the filter belt as the filter belt is passed through one or more vacuum and washing stages. The traveling deckle may be driven by the friction of the deckle against the belt. After the last vacuum point of liquor removal, the deckle returns to its starting point in an endless run. The deckle eliminates conventional curbing and troughing.

BACKGROUND OF THE INVENTION

The present invention relates to horizontal belt washer systems and,more particularly, to a system for controlling slurry on a countercurrent belt washer.

Horizontal belt washers are, in broad terms, the most commonly usedvacuum filters in chemical industry due to their flexibility ofoperation, adaptation to corrosive slurries and suitability to handlelarge throughputs.

On conventional counter current horizontal belt washers, slurry isdeposited on a filter belt. In order to keep the slurry on the filterbelt, some machines incorporate a vacuum carrier belt that is eitherflanged on the edges (these flanges sometimes referred to as curbs orcurbing) or the belt edges are troughed. The curbing is very expensive,very time consuming to vulcanize on the belt and the bond between thecurbing and the belt often breaks, creating leakage. and need forrepair. Some filter belts run in a trough on a carrier belt, or withoutthe carrier belt. Troughing limits the filter belt designs, oftenresults in a loss of vacuum at the trough, reducing liquor removal, andis more demanding of the mechanical splice to make the conveyor beltendless.

As can be seen, there is a need for an improved system for retaining theslurry on a counter current belt washer.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a conveyor system comprises abelt for carrying product on the conveyor; and a traveling deckledisposed along each side of the belt to retain the product on theconveyor, wherein the traveling deckle is separate from the belt andmoves along with motion of the belt by friction between the travelingdeckle and the belt.

In another aspect of the present invention, a counter current beltwasher comprises a filter belt for carrying a slurry on the filter belt;a traveling deckle disposed along each side of the filter belt to retainthe slurry on the filter belt; one or more stationary deckles disposedat edges of the filter belt, wherein the stationary deckles are disposedbetween the slurry and the traveling deckle; a headbox pulley adapted toguide the traveling deckle against a belt edging of the belt, adjacentto the stationary deckle, near a location where the slurry is applied tothe filter belt; and a terminal pulley adapted to guide the travelingdeckle off the belt edging and return the traveling deckle to theupstream pulley at a location where the slurry is self-retained on thefilter belt, wherein the traveling deckle is separate from the belt andmoves along with motion of the belt by friction between the travelingdeckle and the belt.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a counter current belt washer accordingto an exemplary embodiment of the present invention;

FIG. 2 is a side view of the counter current belt washer of FIG. 1 witha traveling deckle;

FIG. 3 is a close-up side view of a traveling deckle terminal pulley ofthe traveling deckle on the counter current belt washer of FIG. 1;

FIG. 4 is a section view taken along line 4-4 of FIG. 2;

FIG. 5 is a section view taken along line 5-5 of FIG. 1;

FIG. 6 is a close-up side view of a traveling deckle headbox pulley ofthe counter current belt washer of FIG. 1; and

FIG. 7 is a close-up side view of the traveling deckle terminal pulleyof FIG. 3, showing a belt tensioning adjustment.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplatedmodes of carrying out exemplary embodiments of the invention. Thedescription is not to be taken in a limiting sense, but is made merelyfor the purpose of illustrating the general principles of the invention,since the scope of the invention is best defined by the appended claims.

Various inventive features are described below that can each be usedindependently of one another or in combination with other features.

Broadly, an embodiment of the present invention provides a travelingdeckle that is adapted to run on each edge of a filter belt in a countercurrent belt washer system. The traveling deckle may be used to retain aslurry on the filter belt as the filter belt is passed through one ormore vacuum and washing stages. The traveling deckle may be driven bythe friction of the deckle against the belt. After the last vacuum pointof liquor removal, the slurry being filtered may be a cake and thedeckle may no longer be needed. The deckle then returns to its startingpoint in an endless run. The deckle eliminates conventional curbing andtroughing.

Referring now to FIGS. 1 through 7, a counter current belt washer 10 mayinclude a filter belt 26 adapted to carry a slurry 34 depositedthereupon by a headbox 36. The slurry 34 may be passed through one ormore vacuum stages and one or more wash stages, as is known in the artfor counter current belt washers.

A headbox pulley 12 may be disposed at each edge of the filter belt 26proximal to the headbox 26. A terminal pulley 18 may be disposed at eachedge of the filter belt 26 at a location downstream of the final washstage. Typically, the terminal pulley 18 may be disposed at a locationalong the filter belt 26 where the cake remaining on the filter belt isfirm and no longer requires an edging along the filter belt 26 to keepthe cake of slurry from coming off the filter belt 26. A travelingdeckle 24 may be adapted to span between the headbox pulley 12 and theterminal pulley 18.

The headbox pulley 12 and the terminal pulley 18 may be disposed tocreate friction between the traveling deckle 24 and a filter belt edging32. This friction may move the traveling deckle 24 along with themovement of the filter belt 26. The traveling deckle 24 may travel alongwith the moving filter belt 26, providing a lip at each edge of thefilter belt 26 to retain the slurry 34 thereupon. One or more deckleguide rollers 40 may keep the traveling deckle 24 from moving off theedge of the filter belt 26. The belt edging 32 may be a sealant,typically of urethane or rubber compounds. Belt edging 32 is typicallyused in a filter belt to chemically lock the porous edges of the filterbelt to protect the belt from unraveling. Typical belt edging 32 isabout 1 inch wide. The filter belt 26 of the present invention may havea belt edging 32 that is wider than the typical 1 inch and wider thanthe traveling deckle 24. In application, the traveling deckle 24 may beinside the edge of the filter belt 26. By sealing the filter belt edgewider than the traveling deckle 24, there may be no vacuum loss in thefilter belt 26 outside of the traveling deckle 24.

The traveling deckle 24 may be removed from the filter belt edging 32 atthe terminal pulley 18. The traveling deckle 24 may then pass over oneor more return pulleys 20 to return back to the headbox pulley 12.

A bath box 22 may be disposed along the return path of the travelingdeckle 24. The bath box 22 may be, for example, stainless steel and maycontain a bath liquid 30. One or more of the return pulleys 20 maydirect the traveling deckle 24 into the bath box 22 to be washed by thebath liquid 30. In some embodiments, the bath liquid 30 may be water. Inother embodiments, the bath liquid 30 may be some other solvent, forexample, one of the wash solvents used in the washing of the slurry 34as it moves along the belt washer system 10.

Referring to FIG. 4, the terminal pulley 18 may be doubled flanged toretain the traveling deckle 24 between its flanges. The traveling deckle24 may be made from a variety of materials, including steel, aluminum,plastic, rubber, composite, urethane, silicone, or the like. In someembodiments, as shown in FIG. 4, a synthetic cord or steel core 38 maybe centrally disposed along the length of the traveling deckle 24. Thereturn pulleys 20 may also be double flanged, similar to the terminalpulley 18.

The headbox pulley 12 may be a single flanged pulley adapted to have itssingle flange on a side away from the filter belt 26. In thisconfiguration, the headbox pulley 12 may deliver the traveling deckle 24adjacent to a stationary deckle 14 that may be disposed from the headbox36 to a position downstream of the headbox 36 where the traveling deckle24 is disposed in the filter belt edging 32. One or more stationarydeckles 14 may be disposed along the belt washer system 10. For example,if a wash liquid may be corrosive to the traveling deckle 24, the washarea along the belt washer system 10 using this corrosive wash liquidmay use a stationary deckle 14 to contain the slurry 34 and thetraveling deckle 24 may simply pass behind the stationary deckle 14.

The terminal pulley 18 may be mounted on a support/tension adjustmentbracket 28. A slot in the bracket 28, for example, may provide amechanism for tightening the traveling deckle 24 to a proper tension.Typically the proper tension would be such that there is no deckle topulley slippage in the traveling deckle 24. The bracket 28 may alsoprovide a mechanism for loosening the traveling deckle 24 to remove itfor repair, inspection or replacement.

While the above description describes a counter current belt washersystem, the design of the present invention may be applicable to othersystems. The present invention could be used on any conveyor thatrequires limiting of controlling the flow of product in a process areaof the conveyor, replacing curbs or belt flanges currently being used tocontain product.

It should be understood, of course, that the foregoing relates toexemplary embodiments of the invention and that modifications may bemade without departing from the spirit and scope of the invention as setforth in the following claims.

What is claimed is:
 1. A conveyor system comprising: a belt for carryingproduct on the conveyor; and a traveling deckle disposed along each sideof the belt to retain the product on the conveyor, wherein the travelingdeckle is separate from the belt and moves along with motion of the beltby friction between the traveling deckle and the belt.
 2. The conveyorsystem of claim 1, further comprising: an upstream pulley adapted toguide the traveling deckle against a belt edging of the belt; and adownstream pulley adapted to guide the traveling deckle off the beltedging and return the traveling deckle to the upstream pulley.
 3. Theconveyor system of claim 2, further comprising one or more guide pulleysadapted to guide the traveling deckle from the downstream pulley to theupstream pulley.
 4. The conveyor system of claim 3, further comprising abath box adapted to contain a bath liquid, wherein one or more of theguide pulleys are adapted to guide the traveling deckle into the bathbox.
 5. The conveyor system of claim 1, further comprising one or moredeckle guide rollers adapted to retain the traveling deckle at the beltedging.
 6. The conveyor system of claim 1, further comprising one ormore stationary deckles disposed at edges of the belt, wherein thestationary deckles are disposed between the product and the travelingdeckle.
 7. The conveyor system of claim 6, wherein the upstream pulleyis a single flanged pulley adapted to deliver the traveling deckleadjacent to at least a portion of the stationary deckle.
 8. A countercurrent belt washer comprising: a filter belt for carrying a slurry onthe filter belt; a traveling deckle disposed along each side of thefilter belt to retain the slurry on the filter belt; one or morestationary deckles disposed at edges of the filter belt, wherein thestationary deckles are disposed between the slurry and the travelingdeckle; a headbox pulley adapted to guide the traveling deckle against abelt edging of the belt, adjacent to the stationary deckle, near alocation where the slurry is applied to the filter belt; and a terminalpulley adapted to guide the traveling deckle off the belt edging andreturn the traveling deckle to the upstream pulley at a location wherethe slurry is self-retained on the filter belt, wherein the travelingdeckle is separate from the belt and moves along with motion of the beltby friction between the traveling deckle and the belt.
 9. The countercurrent belt washer of claim 8, further comprising one or more guidepulleys adapted to guide the traveling deckle from the downstream pulleyto the upstream pulley.
 10. The counter current belt washer of claim 8,further comprising a bath box adapted to contain a bath liquid, whereinone or more guide pulleys are adapted to guide the traveling deckle intothe bath box.